Apparatus for electric generator current control and voltage regulation



1948- H. E. MERRIFIELD 2,448,068

APPARATUS FOR ELECTRIC GENERATOR CURRENT CONTROL AND VOLTAGE REGULATION Filed April 29, 1946 IN VEN TOR. W a W 2 M! Patented Aug. 31, 1948 r 2,448,068

UNITED STATES RATENT OFFICE APPARATUS FOR ELECTRIC GENERATOR CURRENT CONTROL AND VOLTAGE REG- ULATION Harold Edmund Merrifield, Stemmers Run, Md. ApplicationApriI 29, 1946, Serial No. 665,684 3 Claims. (Cl. 322-83) The present invention relates in general to the shunt field to build up and still have the same provision of novel means of automatically conbattery charging rate as before the stoppage of trolling the output of current delivered by low the generator, but instead manual manipulation voltage direct current generators, at the will of for elimination of the shunt field resistance, un-

the operator. The features of invention are parv til the shunt field has been built up, has been reticularly applicable to current control and voltquired for the purpose. age regulation of low voltage generators, such as It is also an object of the invention to provide are used on gasoline, gas and Diesel engines, and a means to supply as nearly as possible a constant wind chargers, in connection-with storage batbattery charging rate regardless of the condition teries, as well as being especially adapted to the of the storage battery. It is also an object of the control of any direct current generator 'used for invention to supply a means of controlling the the charging of storage batteries. charging rate of the storage battery so that in More particularly the invention relates to a cases of equipment running over long periods combination of .a reverse current relay or circuit of time the operator can select a very low chargbreaker, with an extra set of points which are m rate for the s ora a y W h Will be the insulated away from the battery circuit closing same after a shut down, as in the case of autopoints, and are also mounted in such manner as matic stopping and starting, :or for instance, with to open and close in opposite succession to the ene ators driven Withpower which are a tom tbattery circuit closing points of the reverse cur ically started and'stoppe-d or which are started rent relay, and also with a variable resistor 'toand stopped by remote control.

gether with a mode of wiring which permits the Further objects and adva of the invengenerator shunt field to be closed out of series tion are the provision of a new and improved with the variable resistor, when the generator is and greatly simplifie rr nt control and voltnot operating and to stay so-closed-until the age regulator, which allows of fewer failures Shunt field has built up and the generator has of current control than heretofore possible with commenced to deliver current, at which time the p or nown de ices f r t e p pose; which p extra set of points Which are insulated awa from mits the shunt field to build up as fast as posthe battery circuit open, putting the -variable're sible, for instance as fast as the construction of sistor in series with the shunt field. the generator will permit; which allows for the Direct current generators when operating as adjusting 0f e Setting BOIItTQI the Tate heretofore with a high resistance in the shunt of delivery of the current delivered by the genfield circuit, s a to deliver lo rat of generator, at the will of the operator. The current erator output to a storage battery, win t b ild control and voltage regulator of the instant inup after having been shut down, unless thehigh ention is of especial advantage in that the rate resistance is removed from the shunt field cirf rrent delivery by the generator will remain cuit until such time as the shunt field hasbeen Very much more constant than has heretofore able to build up. Furthermore, after the shunt been possible u om al y, and in h t i p rfield, which must be built up before current will m ts t e p at r t e a e to l -s th flow, has been built up again it is necessary to rate of current delivery, and still have the genagain restore to the shunt field the high resist 40 erator put out the same amount of current upon ance which was removed to enable it to build up, eing restarted after a shut down, which is very in order to again deliver the same rate ofcharge desirable, and often ve y necessary, r q pas was being delivered prior to the stoppa e of ment operating under abnormal conditions. With the generator, equipment operating under normal conditions An object and advantage of the i ti i the novel features of the present invention allows also to allow the operator to preselect a storage an Operator o Select he r e t p t e st dambattery charging rate so that when the generator aging the generator a d age battery, an is stopped and restarted the generatorwill 'autow h le t necessary load on h w r plan matically commence to charge the storage batand also allows for a ng of a sto tery at the same rate as before the stoppage. battery in use in connection with equipment run- Heretofore, in the case of restarting a generator g c nstantly, without fear of variation in in which an extremely low rate of charge had the charging rate. Additionally, the control and been selected by the operator prior to the stopregulator. of invention enables an operator to page of the generator, there has been no other select a very low current output rate and still way .of automatically allowing the generator allow the .shunt'field .to buildup without need of manual cutting out resistance placed in the shunt field circuit.

The invention has for further objects such other improvements and such other operative advantages or results as may be found to obtain in the processes or apparatus hereinafter described and claimed.

In the accompanying drawing forming part of this specification, there is shown for purposes of exemplification, a preferred form of apparatus in which the invention may be embodied and practised. In connection with the description of apparatus, there will be given an example of the results obtainable in the practise of the invention.

Figure 1 is a diagrammatic electrical-layout view in plan of apparatus embodying the present invention.

Figure 2 is a diagrammatic view in side elevation illustrating on a larger scale the connection of a reverse current relay or circuit breaker, with an extra set of points for the shunt field circuit, as shown in Figure 1.

As shown in Figure 1, the indicated direct current generator Ill is in connection with any direct current generator system used for purpose of charging of storage batteries, such as are used on gasoline engines, Diesel engines, gas engines and wind charges.

The direct current generator shown in Figure 1 is connected for flow of current to charge a battery by a line connection I8 between the armature of the generator Ill and the movable arm I4 and points I6, I1, of a reverse current relay or circuit breaker II, from which points I6, [1, the current flows to the battery.

For the purpose of regulation and control of the voltage of the generator of a conventional type generator and rate of charge of the battery, a variable resistor 8 is connected in series with the shunt field 9 of the generator II]. 'In the form of the embodiment of the invention chosen for simplicity of illustration there is shown for the purpose a conventional form of rheostat 8 in series with the shunt field, and the armature of the generator is shown connected to the screw I (marked G for generator in Fig. 2) on a conventional form of reverse current relay or circuit breaker II, to which has been added an extra set of points I'2, I3, mounted one on top of the movable arm I4 of the relay for instance, as shown in Fig. 2, and the other on a rigid bar or arm I5, as shown in Fig. 2, and in such manner that the pair of points I2, I3, are in solid contact when the'movable arm I4 of the relay is in a raised position. The bar or arm I4 is mounted in such manner that it has-no electrical contact with the rest of the relay except at the contact points.

The lower pair of pointsIB, H, which are shown in Fig, 2 are used to close the circuit between the battery I8 and the generator I0.

Throughout the drawing and illustrations and also in all written statements and claims, for simplicity of explanation, I am using a one wire system and the ground or frame of the equipment for the other side of the line.

The upper pair of points I2, I3, of the circuit breaker or relay II, one I3 of which is located on the rigid arm or bar I and the other I2 on the top of the movable arm I4, are usedto cut preferably simultaneously and automatically the variable resistance (rheostat) out of the shunt field circuit, and close the direct shunt field circuit between the shunt field lead through the closing the output 4 point I3 on the rigid arm or bar I5 thence through the upper point I2 on the movable arm I4 through the movable arm to the flexible braided wire I9 to the series winding of the relay to the screw marked III for generator on the relay II, thence to the shunt field through a wire connecting the screw on the relay marked In for generator and the shunt field lead, less all appreciable resistance other than that contained in the wiring and the upper set of points I'2, I3, of the relay II all of which time the battery circuit I8 is broken between I6 and I1, and concurrently with the cutting in of the variable resistor 8 (rheostat) the lower point I6 on the movable arm I4 makes contact with the rigid point I! on the bar 2I of the relay proper II',

circuit between the generator I0 and battery I8 through the screw marked I8 for battery on the relay II and the lead to the battery. When the movable arm I4 of the relay II is pulled down to close the battery circuit it also concurrently opens the direct portion of the shunt field circuit aand automatically places the variable resistor 8 (rheostat) in series with the shunt field.

In operation when the generator is started from stand still, the movable arm I4 remains in the position shown in Fig. 2, under the action of its spring 20 until the shunt field has built up and commenced to deliver current at a sufficient rate to energize the magnetic coil of the relay II which in turn draws the movable arm I4 of the relay down to close the output circuit'between the generator I0 and the battery I8 by contact of the lower point I6 located on the movable arm I4 with the stationary point II located on the stationary bar 2I of the relay proper II, on which bar 2I is located the screw marked I8 for battery, whereupon current flows from the armature through the series coil of the relay I I and thence to the battery I8. The downward movement of the movable arm I4 concurrently breaks the contact between the upper set of points I2, I3, simultaneously opening the direct circuit portion of the shunt field circuit comprising the movable arm I4 and series coil of the relay II and the armature lead 9 from the generator I0, and automatically placing the variable resistor 8 in series with the shunt field. Until the time that the contact between the upper pair of points I2, I3, is broken, the shunt field circuit by-passes the variable resistor 8 (rheostat), the field flow being through the shunt field lead 9, the upper set of contact points I2, I3, movable arm I4, series coil II and armature lead II]. When however the shunt field has built up sufllciently to permit the generator ID to produce current the movable arm I4 is' retracted against its spring 20 and the battery circuit I8 is closedby the contact of the lower set of points I6, I1; and the variable'resistor 8' (rheostat) is placed in series with the shunt fieldcircuit and the direct portion of the shunt fieldcircuit (that is the portion from the shunt field lead 9 to the upper relay contact point I2, through'the movable arm I4 through the series coil and armature lead) is opened; whereupon the shunt field flow is through the shunt field lead, the variable resistor (rheostat) finger, the resistor 8 and thence to the armature lead. r

It will of course be understood that the extra set of points I2, I3, used in control of the'shunt field can'be mounted in many other mechanical ways with the same result. 'It'will also be:understood that in event of a two wire system being used, the .points are used in one side'only of the shunt field circuit. It-will also'be understood thatthe invention herein described is not to be-limited in all its aspects to the novel use shown herein of a conventional .type of relay or circuit breaker which is of especial utility in conjunction with this circuit, since it will be apparent that this shunt field control circuit can be connected in other ways and otherwise used inj'practical use of the circuit in the. control of generator shunt fields. For example instead of mounting the extra point l3 on the rigid arm or bar. 15,"which is used for by-passing the variable resistor 8 (rheostat), the extra point i 3 can be mounted on and through the metal cover of the conventional type of relay or circuit breaker of course keeping the point insulated awayfrom the cover and mounted in such manner as to be rigid and to make good and sufiicient contact with the point i 2 on the movable arm 14 or relay I4.

In any case disregarding the method of mounting, the cutting of the variable resistor 8 in and out of the shunt field circuit takes place automatically and simultaneously with the cutting in and out of the battery circuit [8. In instances it may be desirable not to have the variable resistor.8 cut in simultaneously with the cutting in of the battery circuit l8 but to have the same take place stepwise or by means of delayed action aifording an interval of time before they both are simultaneously cut in. This nevertheless may readily be made to take place with the present invention while still retaining the novel features for automatically by-passing the shunt field circuit variable resistor 8, when the battery circuit I8 is broken and for automatically cutting in the former when the circuit for the latter is closed.

From the foregoing it will be seen that the novel features of the present invention affords the operator the choice of pre-selecting a constant battery charging rate or having complete control at all times of the full range of the capacity of the generator to compensate for any change in operating conditions. Also it will be seen that the novel features of the invention afiords the operator the choice of selecting a charging rate that will not change upon the driving power being shut ofi and the equipment put back in operation. This latter feature is especially desirable in cases of stationary equipment started and stopped manually or by remote control. These latter features are made possible only by the fact that the invention allows the generator shunt field to build up with a very high resistance in the shunt field circuit wiring system but with the resistance bypassed until such time as the shunt field has built up. After shutdown of the equiqment, the variable resistor 8 (rheostat) shunt field control circuit is automatically cut out and maintained out of the shunt field circuit, While the battery circuit is broken, and until the battery circuit I8 is closed again by the flow of the required current from the generator l0. Whereupon the shunt field control circuit, containing the variable resistor 8 (rheostat) is automatically cut into shunt field. It thus will be seen that the variable resistor 8 (rheostat) may be set for delivery of a much lower rate of generator output, independently of the building up of the shunt field to the extent required for generating and delivering current, than would be possible automatically to do without this invention. It will be further seen that this shunt field control circuit is no longer limited to one that must be pre-set' at aa-fixed settingconsistent with the inherent peculiarities of the particular generator but maybe reset at the will of the operator in the course of the use of the system by means readily accessible to the operator,,for example by accessible means for adjusting the finger 22 of the variable resistor 8 (rheostat) relative to the rneostat contact points, as by adjustable means on an automobile instrument panel for variable resistor (rheostat) finger. .ZIn thisconnection one advantageous use of the instant improvement, in connection with gasoline, gas, and Diesel engine driven vehicles, is that it enables the operator to, at will, increase the resistance in the shunt field circuit'and thus cut down the rate of the generator current output in the course of long trips, or sustained operation by stationary equipment, making unnecessary the burning of lights, or fear of failure of the present conventional type of regulation; to consume or regulate the excess current effectively to avoid overcharging the battery or charging the battery at too high a rate over sustained periods of time, or damaging the generator through an excessive high output rate caused by heat within the generator. It also enables an operator to reset at will the variable resistor c (rheostat) at any desired higher rate desired of which the generator to may be capable of producing to compensate for any extra loads on the battery 8, which may be caused by excess usage of such equipment as radios, heaters, cigar lighters, extra lights, air conditioning systems, electric windshield wipers, fog lights, truck running and marker lights, bus interior and exterior lighting and radio telephones, and also excess stopping and starting. The improved features of invention are also especially applicable for regulation and control in a simple, economical and greater facile way for accurate, constant, sustained control of battery charging rates in wind charger operation, and for use in connection with Diesel electric cranes, drag lines, excavators, tractors, railroad locomotives, train lighting systems, train air conditioning systems, and all electrically started internal combustion engines.

It can be readily seen that by the use of the novel features of the invention it is possible for the operator to select the lowest rate of output necessary to keep the battery charged which in turn allows for a consequent saving of fuel in the prime mover for the reason that it takes considerable horsepower to pull a generator operating under excessive output and correspondingly less amounts of fuel with lesser loads.

The variable resistor (rheostat) and ohm range as shown in Fig. 1 is just one of the many types and kinds of variable resistors that can and may be used in conjunction with the present invention. As shown, AB= ohm, B-C=% ohm, CD=1 ohm, DE=l ohms, and the wire is 5 amp. capacity #16 wire. However, it will be readily seen that the invention is in no wise limited to any particular variable resistor, but on the contrary applies to any variable resistor capable of covering the full range of the capacity of the shunt field of the particular generator to which the instant invention is applied. Consequently, it will be readily seen that the illustration in regard to ohm variation of the variable resistor and size of wire and ampere capacity is only placed on the drawing for purposes of illustration of any of the many Ways for controlling the'shunt field of a direct current generator as applied to the instant invention; I The indicating'light as shown in 'Figureil is used on the drawing for purposes of showing one means of allowing the operator to be able'to see at a glance whether or not the generator is operating. It will be readily seen that many other indicating devices can and may be used in conjunction with the instant invention for the above purpose, for instance ammeters, voltmeters, buzzers and bells.

The invention as herein above set forth is embodied in particular form and manner but may be variously embodied within the scope of the claims hereinafter made.

I claim:

1. An automatic controlling device for a direct current generator having a shunt field, comprising a variable resistance connected in series with the shunt field, and a reverse current circuit breaker for connecting the generator to a battery to be charged, an electrical make and break switch connected in shunt with the variable resistance and operated directly by and substantially simultaneously with operation of the reverse current circuit breaker with the make and break switch closed when the reverse current circuti breaker is open, for cutting the variable resistance out of series with the shunt field when the reverse current circuit breaker opens the battery circuit, and for cutting the variable resistance back in series with the shunt field when the reverse current circuit breaker closes the battery circuit.

2. An automatic controlling device for a direct current generator having a shunt field and a circuit external to the shunt field, comprising a variable resistance connected in series with the shunt field, and a reverse current circuit breaker for connecting the generator to the external circuit, an electrical make and break switch connected so as to shunt out the variable resistance and operated directly by and substantially simultaneously with operation of the reverse current circuit breaker with the make and break switch closed whenever the reverse current circuit breaker is open, for cutting the variable resistance out of series with the shunt field when the reverse current circuit breaker opens the external circuit, and for cutting the variable resistance back in series with the shunt field whenever the reverse current breaker ternal circuit.

3. Automatic apparatus for direct-current eleccloses the extrio-generator current control-and voltage regti lation of an'electrical system'com'prising a variable resistor, a direct current generator, an armature therefor, and a storage battery, which apparatus comprises a reverse current relay with a movable arm having a set of points for connecting the generator to the battery and having an extra set of points of sufficient current capacity to carry the shunt field load of the generator and which extra set of points are also mounted with a suflicient air gapv to make good and sufficient provision for breaking the shunt field circuit, one of said extra set of points being mounted on the upper outer side of a movable arm of the relay and the other of said points being mounted in such manner that it is rigid and insulated completely away from the balance of the reverse current relay and in such rigid manner that the former point will come in solid contact with the latter point of the relay, when the movable arm is released from the pull of the magnetic coil of the reverse current relay, a terminal of suflicient electrical capacity to carry the shunt field circuit of the generator directly connected to said latter of said points, a lead from said terminal to the contact finger of the variable resistor, said Variable resistor being of suificient capacity to control the full range of the generator shunt field of the generator, another lead connected to lead from a terminal of the variable resistor and thence to the armature, another lead connected to lead from the battery terminal of the reverse current relay to the storage battery, another lead connected to lead from the shunt field of the direct current generator to the terminal which is electrically connected to the extra point that is mounted rigid and insu lated completely away from the balance of the reverse current relay, and another lead connected from the generator terminal of the reverse current relay to the armature of the generator, the ground or frame of the equipment being the opposite side of the circuits.

HAROLD EDMUND MERRIFIELD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,288,938 Leonard Dec. 24, 1918 2,135,977 Leece Nov. 8, 1938 

